Periictal heart rate variability analysis suggests long-term postictal autonomic disturbance in epilepsy

Background: One of the possible pathomechanisms of sudden death in epilepsy (SUDEP) is a postictal dysregulation of autonomic nervous system. We performed a heart rate variability (HRV) analysis of the periictal state to analyze whether a cardiac autonomic disturbance exists after an epileptic seizure. Methods: We included 31 periictal video–EEG–ECG recordings of 31 patients with epilepsy who had consecutively undergone pre-surgical evaluation. Nine generalized tonic-clonic (GTCS), 15 complex partial, and seven simple motor seizures were included. HRV was evaluated by analyzing 5-min-long ECG epochs, sampling from baseline, direct preictal, early-postictal (<15 min after the seizure), and late-postictal (5–6 h after the seizure) periods. Results: The heart rate was elevated immediately after the seizures, but 5–6 h postictally returned to the baseline level. Time-domain components of HRV decreased after the seizure and this decrease lasted for 5–6 h. Low-frequency power decreased in the early-postictal phase and high-frequency power of HRV dropped in the late-postictal phase. GTCS had an impact on short-term but not on long-term postictal HRV decrease. Conclusions: We found decreased HRV immediately after the seizures, which lasted at least 5–6 h postictally, indicating a long-term postictal disturbance of the autonomous nervous system. GTCS were accompanied by a more decreased HRV than other seizures. Our results may have relevance in explaining pathomechanism of SUDEP